Modular resistance force system

ABSTRACT

A modular resistance force system includes an axle configured to be rotatable around a rotational axis and one or more resistance mechanisms. Each of the one or more resistance mechanisms includes a resistance element disposed about a portion of the axle, a resistance element housing configured to house the resistance element and a resistance substance disposed between the resistance element and the resistance element housing. Either the resistance element or the resistance element housing is selectively engaged to rotate with the axle. A resistance between the resistance element and the resistance substance causes a force to be applied to the axle when the resistance element and the resistance element housing move relative to each other.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/753,729 filed Jan. 17, 2013, which is incorporated herein withreference in its entirety.

TECHNOLOGY FIELD

The present invention relates in general to a modular resistance forcesystem and more particularly, to a device and method for providing amodular resistance force for use in exercise and therapeutic products.

BACKGROUND

Physical fitness studies often credit physical exercise with addingyears to one's life, making them both healthier and happier, on average.Despite these significant benefits, many people do not exercise for arange of reasons. Most people are limited by the time, space, or moneythey have available for exercise. Free weights and stacked weightmachines have a prohibitively large footprint for a home and can bequite dangerous by trapping the users beneath weighted barbells orhurting little fingers between the moving plates. Popular home fitnessproducts that use an inclined ramp or pushup handles offer only somepercentage of one's bodyweight as its maximum resistance level.Inadequate resistance levels can lead to repetitive strain injuries fromthe number of repetitions needed for muscle fatigue even at moderatefitness levels. Dumbbells sets may be used as alternatives to largefitness machines but are quite expensive and limit resistance trainingto the upper body. Conversely, cardio cycles, treadmills, climbers androwers work well for the lower body but provide limited value inbuilding upper body strength. These machines are also expensive and usesignificant space in the home. Cheaper options such as rubber bands andshakable dumbbells, although portable and inexpensive, have resistancecurves which are a poor match for the strength curve of a muscle.

Commercial gyms may be an option for a total body workout, but are oftencostly and, time consuming when adding in travel times to workout time.Individuals with physical limitations often find that the weight systemsavailable to them in commercial gyms do not accommodate theirwheelchairs or walkers. Many individuals are too self-conscious of theirweight or lack of strength to exercise and feel good about themselves incommercial gyms. In addition to these challenges, fitness novices, aswell as our growing elderly population, often suffer from debilitatingpain in their muscles that are not accustom to exercise. This commoncondition is called Delayed Onset Muscle Soreness, clinically referredto as (DOMS). DOMS causes muscles to be tight and painful afterexercise. Although most of us have experienced mild discomfort from DOMSafter a workout or physical event, DOMS can be so intense thatindividuals significantly limit the range of movement of the effectedmuscles for several days in order to avoid the intense pain. Further,unpredictable business travel schedules and simple mental boredom caneasily discourage all but the most determined to achieve their fitnessgoals. A simpler and more cost effective exercise system is needed.

SUMMARY

Embodiments of the invention are directed to a modular resistance forcesystem that includes an axle configured to be rotatable around arotational axis and one or more resistance mechanisms. Each of the oneor more resistance mechanisms includes a resistance element disposedabout a portion of the axle, a resistance element housing configured tohouse the resistance element and a resistance substance disposed betweenthe resistance element and the resistance element housing. Either theresistance element or the resistance element housing is selectivelyengaged to rotate with the axle. A resistance between the resistanceelement and the resistance substance causes a force to be applied to theaxle when the resistance element and the resistance element housing moverelative to each other.

According to one embodiment, the resistance between the resistanceelement and the resistance substance causes a force to be applied to theaxle in a first rotational direction.

In one embodiment, the force is applied to the axle when the resistanceelement is selectively engaged to rotate and the resistance elementhousing is stationary. In another embodiment, the force is applied tothe axle when the resistance element housing is selectively engaged torotate and the resistance element is stationary.

In one aspect of an embodiment, the resistance element is a disc or acylinder.

According to one embodiment, the resistance substance is a fluidcomprising at least one of silicone, grease, such as silicon grease,rubber, an adhesive, or a high tensible or viscous material.

According to another embodiment, the modular resistance force systemfurther includes one or more resistance engaging devices each configuredto have selectable states that include: (i) an engaging state whichcauses the resistance element and the resistance element housing to moverelative to each other and causes the force to be applied to the axle;and (ii) a disengaging state which allows the corresponding resistanceelement housing and the corresponding resistance element to movetogether.

In one aspect of an embodiment, the corresponding resistance elementhousing include protrusions and the one or more resistance engagingdevices prevents the corresponding resistance element housing fromrotating by engaging the protrusions.

In one embodiment, the one or more resistance mechanisms include aplurality of resistance mechanisms sharing the rotational axis and theproduct of the resistant forces of each of the plurality of resistancemechanisms is equal to a total force applied to the axle in the firstrotational direction.

In another embodiment, the plurality of resistance mechanisms include afirst resistance mechanism configured to apply a first force to the axlewhen a first resistance element and a first resistance element housingof the first resistance mechanism move relative to each other. Theplurality of resistance mechanisms also include a second resistancemechanism configured to apply a second force to the axle when a secondresistance element and a second resistance mechanism housing of thesecond resistance mechanism move relative to each other. The first forceand the second force are different.

According to one embodiment, the plurality of resistance mechanismsinclude a first resistance mechanism and a second resistance mechanism.The first resistance mechanism is coupled to the second resistancemechanism via a joining element.

According to one embodiment, the modular resistance force system furtherincludes a spool mechanism having a coilable-uncoilable elementconfigured to cause the axle to rotate in a second rotational directionopposite the first around the rotational axis when thecoilable-uncoilable element uncoils around the rotational axis. Thespool mechanism also has at least one spring-force mechanism coupled tothe coilable-uncoilable element and configured to apply a spring forceto cause the coilable-uncoilable element to coil around the rotationalaxis.

According to one aspect of an embodiment, the modular resistance forcesystem further includes a spool mechanism locking device configured toprevent the coilable-uncoilable element from uncoiling and coilingaround the rotational axis.

Embodiments of the invention are directed to a modular resistance forcesystem that includes an axle configured to be rotatable around arotational axis and a plurality of resistance elements disposed aboutportions of the axle. The modular resistance force system also includesa housing configured to house the plurality of resistance elements and aresistance substance disposed between the plurality of resistanceelements and the resistance element housing. Either the resistanceelement or the resistance element housing is selectively engaged torotate with the axle and cause a force to be applied to the axle.

According to one embodiment, the one or more resistance elements areselectively caused to move relative to the housing.

Embodiments of the invention are directed to a modular resistance forcesystem that includes an axle configured to be rotatable around arotational axis and one or more resistance mechanisms. Each of the oneor more resistance mechanisms includes a resistance element disposedabout a portion of the axle, a resistance element housing configured tohouse the resistance element and a resistance substance disposed betweenthe resistance element and the resistance element housing. Either theresistance element or the resistance element housing is selectivelyengaged to rotate with the axle and cause a force to be applied to theaxle. The modular resistance force system also includes one or moresensors configured to sense information associated with at least one of:(i) the axle; and (ii) the one or more resistance mechanisms. Themodular resistance force system further includes a communications systemconfigured to at least one of: (i) transmit the sensed informationreceived from the one or more sensors to one or more external devices;and (ii) receive external information from the one or more externaldevices.

According to one embodiment, the modular resistance force system furtherincludes a switch that causes the resistance element and the resistanceelement housing to move relative to each other. The one or more sensorsis further configured to sense information associated with the switch.

According to one embodiment, the modular resistance force system furtherincludes a coilable-uncoilable element configured to cause the axle torotate in a second rotational direction opposite the first around therotational axis when the coilable-uncoilable element uncoils around therotational axis. The modular resistance force system further includes aspindle configure to rotate with the coilable-uncoilable element. Theone or more sensors is further configured to sense informationassociated with the spindle.

According to one aspect of an embodiment, the one or more sensors areoptical sensors.

In one embodiment, the communications system includes a networkinterface configured to at least one of: (i) transmit the sensedinformation to the one or more external devices via one or more networkswired or wirelessly and (ii) receive the external information from theone or more external devices via the one or more networks wired orwirelessly.

In another embodiment, the sensed information is information indicatingat least one of: a number of rotations of the axle; a rate of rotationsof the axle over a period of time; a stroke length; and an amount ofresistance applied to the axle.

According to one aspect of an embodiment, the one or more sensorsincludes a heart rate sensor configured to sense the heart rate of auser.

According to one embodiment, the modular resistance force system furtherincludes a processor configured to cause the communications system totransmit the sensed information received from the one or more sensors tothe one or more external devices and the communications system toreceive the external information from the one or more external devices.

According to one embodiment, the modular resistance force system furtherincludes a memory having instructions for causing the processor toinstruct the communications system to transmit the sensed informationreceived from the one or more sensors to the one or more externaldevices and receive the external information from the one or moreexternal devices.

In one embodiment, the modular resistance force system further includesan electronic switch configured to cause the resistance element and theresistance element housing to move relative to each other and allow theresistance element housing and the resistance element to move together.

Embodiments of the invention are directed to a fitness system thatincludes one or more modular resistance force systems and an externalmechanism. The one or more modular resistance force systems each has anaxle configured to be rotatable around a rotational axis and one or moreresistance mechanisms. Each of the one or more resistance mechanismsincludes a resistance element disposed about a portion of the axle, aresistance element housing configured to house the resistance elementand a resistance substance disposed between the resistance element andthe resistance element housing. Either the resistance element or theresistance element housing is selectively engaged to rotate with theaxle and cause a force to be applied to the axle. The external mechanismhas one or more components configured to interact with a user and theone or more modular resistance force systems is coupled to the externalmechanism.

According to one embodiment, the external mechanism is a home fitnessproduct from a group of home fitness products that includes a stationarybicycle, a climbing product and a rowing product.

According to another embodiment, the external mechanism is a productthat applies a rotational resistance force.

In one aspect of an embodiment, the external fitness mechanism is aproduct applies a linear resistance force. In another aspect of anembodiment, the external fitness mechanism is a product that usesgravity to apply a resistance force.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the present invention are bestunderstood from the following detailed description when read inconnection with the accompanying drawings. For the purpose ofillustrating the invention, there is shown in the drawings embodimentsthat are presently preferred, it being understood, however, that theinvention is not limited to the specific instrumentalities disclosed.Included in the drawings are the following Figures:

FIG. 1 is a cutaway view of an exemplary modular resistance force systemthat can be used with embodiments disclosed herein;

FIG. 2 is an exploded view of the exemplary modular resistance forcesystem shown at FIG. 1;

FIG. 3 is an assembly drawing that illustrates the axle coupled to thespindle sprocket and a resistance mechanism that can be used withembodiments disclosed herein;

FIG. 4 is an axonometric drawing of a portion of a spool mechanismcoupled to the axle that can be used with the embodiments disclosedherein;

FIG. 5A is an axonometric drawing of an exemplary modular resistanceforce dumbbell system that can be used with the embodiments disclosedherein;

FIG. 5B is a cross sectional view of the exemplary modular resistanceforce dumbbell system shown at FIG. 5A;

FIG. 5C is an axonometric drawing of the exemplary modular resistanceforce dumbbell system shown at FIG. 5A;

FIG. 6 is an axonometric drawing an exemplary modular resistance forcesystem having a holding device and foot element that can be used withthe embodiments disclosed herein;

FIG. 7 is an axonometric drawing of an exemplary modular resistanceforce system holding an exercise bar pulled by a user that can be usedwith the embodiments disclosed herein;

FIG. 8 is a list of embodiments of one or more modular resistance forcesystems;

FIG. 9 is an axonometric drawing of a fitness system having multiplemodular resistance force systems stacked together to produce a combinedforce that can be used with the embodiments disclosed herein;

FIG. 10 is a block diagram of an exemplary fitness system that includesa modular resistance force system in communication with an externaldevice that can be used with the embodiments disclosed herein;

FIG. 11 is an axonometric drawing of an exemplary modular resistanceforce system electronically coupled to a computer that can be used withthe embodiments disclosed herein;

FIG. 11A is a close-up view of the exemplary modular resistance forcesystem shown at FIG. 11;

FIG. 11B and FIG. 11C are axonometric drawings that illustrate differentphysical states of the exemplary modular resistance force system shownat FIG. 11;

FIG. 12 is a block diagram of a processing system of an externalelectronic device that can be used with the embodiments disclosedherein;

FIG. 13A through 13D illustrate external fitness products that may beused with the embodiments disclosed herein;

FIG. 14 illustrates resistance elements having some of the differentsurface geometries that may be used with the embodiments disclosedherein;

FIG. 15 is a drawing illustrating a modular resistance force system thatmay be used with jump training;

FIG. 16 is a drawing illustrating a modular resistance force system thatmay be used with weight training;

FIG. 17A through FIG. 17D are drawings illustrating modular resistanceforce systems that may be used for physical rehabilitation; and

FIG. 18A through FIG. 18C are axonometric drawings of an exemplarymodular resistance force system having a plurality of resistanceelements and a single stationary outer housing that can be used with theembodiments disclosed herein.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention provide a cost effective andportable modular resistance force system. Embodiments of the presentinvention provide resistance which allows users to build concentricstrength or the strength needed to move an object at rest withouteccentric resistance, which has been shown to be the leading cause ofDOMS. Embodiments of the present invention include one or more modularresistance force systems coupled to external components of variousexercise fitness systems. Embodiments of the present invention usesensors to provide information about the duration, intensity and numberof repetitions associated with the user's exercises that can be sharedwith the users or others, including doctors, physical therapists,trainers and sports teams. Embodiments of the present invention outputdata to supplement electronic game play, create historical data ofperformance or provide feedback to modify the resistance or othersettings.

FIG. 1 to FIG. 5 show various views and components of an exemplarymodular resistance force system 100. The modular resistance force system100 will now be described with reference to FIG. 1 to FIG. 5. As shown,the modular resistance force system 100 may include an axle 102configured to be rotatable around a rotational axis 108 and resistancemechanisms 106 a, 106 b, 106 c and 106 d. Although the embodiment shownat FIG. 1 to FIG. 5 includes four resistance mechanisms, embodiments mayinclude any number of resistance mechanisms. As shown, each resistancemechanisms 106 a, 106 b, 106 c and 106 d may include a resistanceelement 122 disposed about a portion of the axle 102, a resistanceelement housing 124 configured to house the resistance element 122 and aresistance substance 126 disposed between the resistance element 122 andthe resistance element housing 124. The geometry of the resistanceelements 122 and the resistance element housings 124 shown in theembodiment shown at FIG. 1 to FIG. 5 are merely exemplary. Embodimentsmay include resistance elements 122 having any geometries, such as adisc or cylinder, and resistance element housings 124 having anygeometries such that a resistance of substance 126 between surfaces ofthe resistance elements 122 and the resistance element housings 124applies a force to the axle 102, such as the force in a first rotationaldirection 115 described in more detail below.

Resistance elements 122 and resistance element housings 124 may includeone or more materials such as plastics, metals, composites, ceramics,woods and other solid materials. Resistance substances 126 may be afluid, a solid or a gel. Resistance substances 126 may include one ormore materials such as silicone. Resistance substances 126 may beadhesives, which include sticky substances such as fugitive adhesives,highly viscous fluids, grease, such as silicon grease, or viscosityenhanced fluids, such as liquid latex, sticky fluids, rubber-like semifluids or gels and semi-solids, such as gelatinous solids. Factors fordetermining the materials of the resistance element 122, a resistanceelement housing 124 and a resistance substance 126 may include wear,temperature, amount of resistance between the materials, force needed toovercome initial inertia, durability, recovery, tensile strength andstickiness.

Each resistance element 122 may be attached to the axle 102 andconfigured to rotate with the axle 102 around the rotational axis 108.Each resistance element housing 124 may be configured to house acorresponding resistance element 122 and resistance substance 126. Eachresistance substance 126 may be disposed between a correspondingresistance element 122 and a corresponding resistance element housing124. Accordingly, each resistance element housing 124 may be coupled toa corresponding resistance element 122 via a corresponding resistancesubstance 126.

Rotation of the axle 102 causes each of the resistance elements 122attached to the axle 102, each resistance substance 126 and eachresistance element housing 124 to rotate with the axle in a secondrotational direction 112. When each of these components 122, 124 and 126move together, no resistance force is applied to the axle 102. When aresistance element 122 and a corresponding resistance element housing124 move relative to each other, however, a resistance between theresistance element 122 and the corresponding resistance substance 126causes a force to be applied to the axle 102 in the first rotationaldirection 115, opposite the second rotational direction 112.

According to embodiments of the present invention, one or moreresistance elements 122 and corresponding resistance element housings124 may be caused to move relative to each other by selectively engagingeither the resistance elements 122 or the resistance element housings124 to rotate with the axle 102. In some aspects, one or more resistanceelements 122 and corresponding resistance element housings 124 may becaused to move relative to each other when the one or more resistanceelements 122 are selectively engaged to rotate and the correspondingresistance element housings 124 are stationary. In other aspects, theforce may also be applied to the axle 102 when the one or moreresistance element housings 124 are selectively engaged to rotate andthe corresponding resistance element 122 are stationary. In yet otheraspects, one or more resistance elements 122 and correspondingresistance element housings 124 may be caused to move relative to eachother by moving the resistance elements 122 or the resistance elementhousings 124 slower than the other or by moving the resistance elements122 or the resistance element housings 124 in the opposite direction ofthe other.

In some embodiments, resistance engaging devices 128 may be used to movethe resistance elements 122 and the resistance element housings 124relative to each other. For example, as shown at FIG. 1, modularresistance force system 100 may include resistance engaging devices 128configured to have selectable states. When an engaging state of aresistance engaging device 128 is selected (e.g., pressed by a user),the movement of a corresponding resistance element housing 124 may bechanged (e.g., stop movement, move slower, and move in the oppositedirection).

For example, resistance engaging device 128 b may enter an engagingstate when a resistance engaging device portion 130 is moved to aposition abutting a resistance element housing protrusion 132. In thisengaging position, when the axle 102 rotates, the resistance elementhousing 124 of resistance mechanism 106 b may be prevented from rotatingwhile the corresponding resistance element 122 rotates with the axle102. Accordingly, a force may be applied to the axle 102 responsive tothe resistance between the resistance element 122 and the correspondingresistance substance 126. As described above, however, in otherembodiments, the force may be applied to the axle 102 by moving theresistance element 122 slower and/or moving the resistance element 122in the opposite direction.

When a disengaging state of a resistance engaging device 128 isselected, the one or more resistance element housings 124 and thecorresponding resistance elements 122 are allowed to move together. Forexample, resistance engaging device 128 b may enter a disengaging statewhen a resistance engaging device portion 130 is moved to a positionaway from a resistance element housing protrusion 132. In thisdisengaging position, when the axle 102 rotates, the resistance elementhousing 124 of resistance mechanism 106 b may rotate while thecorresponding resistance element 122 is also rotating. In otherembodiments, modular resistance force systems may include differenttypes of resistance engaging devices configured to prevent a resistanceelement housing from rotating.

It is also contemplated that resistance element housings 124 may befixedly coupled so that they are stationary and resistance engagingdevices 128 may cause one or more resistance elements 122 to move whilethe corresponding resistance element housings 124 are stationary. Forexample, resistance engaging devices 128 may cause one or moreresistance elements 122 to move using one or more clutches (not shown),each coupled to a corresponding resistance element 122. When engaged,the clutches may cause the corresponding resistance elements 122 torotate with the axle 102 while the corresponding resistance elementhousings 124 are stationary, thereby causing a force to be applied tothe axle 102.

In some embodiments, a modular resistance force system may include aplurality of resistance elements moving relative to a single stationaryouter housing. For example as shown at FIG. 18A, the system 1800 mayinclude an axle 1802 having segments. Embodiments may include axleshaving any number of segments. A plurality of resistance elements 122disposed about portions of the axle 1802. As shown, the system 1800 mayalso include a single housing 1804 configured to house the plurality ofresistance elements 122 and a resistance substance 126 disposed betweenthe plurality of resistance elements 122 and the housing 1804. Strap 123can be coiled around a protruding portion of axle 1802, causing axel1802 to rotate relative to housing 1804 when a user lifts housing 1804.Resistance elements 122 provide a resistance force between axel 1802 andhousing 1804 when lifted. Embodiments may include resistance elementshaving any geometry. As shown at FIGS. 18B, and 18C, resistance elements122 may be selected to add resistance or not add resistance when alocking device, such as sleeve 1806 is moved between locked and unlockedpositions. For example, when sleeve 1806 is in the position shown inFIG. 18B, axle segment 1802 a and axle segment 1802 b are unlocked andthe sleeve 1806 does not connect axle segment 1802 a and axle segment1802 b. Accordingly, the outer resistance element 122 b does not rotate.When sleeve 1806 is in the position shown in FIG. 18C, axle segment 1802a and axle segment 1802 b are locked together and inner resistanceelement 122 a the outer resistance element 122 b rotates relative tohousing 1804.

As shown in FIG. 18B, additional removable resistance elements can beadded manually, in some embodiments. Exemplary removable resistanceelement 125 can be manually coupled to system 1800 to increaseresistance a desired amount. The resistance element portion of removableresistance element 125 can be coupled to axle 1802, while the housingportion of removable resistance element 125 can be coupled to housing1804, allowing removable resistance element 125 to increase theresistance as axle 1802 rotates relative toe housing 1804. Various sizesor resistances of removable resistance elements may be added to allow auser to personalize resistance when using system 1800. In someembodiments, multiple removable resistance elements can be added in astacked manner, allowing resistance to be further customized.

As shown at the embodiment at FIG. 1, the system 100 may include acoilable-uncoilable element 110. When the coilable-uncoilable element110 is pulled in the direction indicated by arrow 114, thecoilable-uncoilable element 110 uncoils around the rotational axis 108,causing the axle 102 to rotate in the second rotational direction 112.The coilable-uncoilable element 110 may be of varying lengths and widthsand may include any material configured to cause the axle 102 to rotate,such as nylon webbing. As described below, however, axles in otherembodiments may be caused to rotate without coilable-uncoilableelements. For example, belts, such as belts 1302 and 1304 shown at FIG.13B and FIG. 13D respectively, may be used to transfer the resistanceforce to other elements, such as wheels and pedals.

As shown at the embodiment at FIG. 1, the coilable-uncoilable element110 may be part of a spool mechanism 104 that also includes at least onespring-force mechanism, such as spring 120 configured to apply a springforce to cause the coilable-uncoilable element 110 to coil around therotational axis 108. As shown, spool mechanism 104 may also include anda clutch 116 coupled between the coilable-uncoilable element 110 and thespring 120 and configured to engage the axle 102. As shown, one end ofthe spring 120 may be coupled to the clutch 116 via a lower coupler andanother end of the spring 120 may be coupled to an outer housing, suchas spherical shell 134, via upper coupler 122. When a force (e.g., froma user) causing the coilable-uncoilable element 110 to move in thedirection 114 is no longer applied, the constant recoil force may recoilthe clutch 116, causing the coilable-uncoilable element 110 to recoil toits initial position.

In some embodiments, a spool mechanism locking device 136 may beincluded to prevent the coilable-uncoilable element 110 from uncoilingand coiling about the rotational axis 108. For example, the spoolmechanism locking device 136 may be configured to have selectable recoilstates. A locked state may be selected (e.g., by pressure from a user)which prevents the coilable-uncoilable element 110 from uncoiling whenspool mechanism locking device 136 abuts a tooth on one or both of ssprockets 113. A unlocked state may also be selected which allows thecoilable-uncoilable element 110 to uncoil. By coupling the modularresistance force system 100 to a stationary external object, a user maystretch thereby increasing flexibility while pulling on thecoilable-uncoilable element 110 while in the spool locked state. In someembodiments, one or more systems 100 may be locked down (e.g., via asingle beam) to an external fitness product (e.g., a workout gym).

In the embodiments described above, the force applied to the axle 102remains substantially constant at a constant velocity. Minor variationsto the force remaining constant occur due to changes in heat over timeand overcoming inertia.

Physiologists have identified “eccentric muscle contractions” as beingthe greatest cause for Delayed Onset Muscle Soreness (DOMS). This typeof movement is sometimes called the “doing a negative” in fitness gyms.The pain caused by DOMS often results in temporary loss of range ofmotion in major muscle groups performing an exercise. When pain limitsthe movement of muscles, individuals bodies will recruit other musclesthat are pain-free for given tasks. These muscle groups typically do nothave the same strength or mechanical advantage of the primary musclegroup that are in pain. This recruitment of other muscle groups may beparticularly hazardous to the elderly if painful leg muscles (e.g.,needed to descend a staircase) are not adequate. If part of the way downthe stairs, the elderly person must rely upon their arms and handsholding onto the railing in order to control their downward descent,fatigue due to inadequate upper body strength could result in a lifealtering or life ending fall. Because the user does not experience anyresistance as the coilable-uncoilable element 110 recoils, however, thepain associated with DOMS and the above described ramifications areexpected to be greatly reduced.

The product of the forces applied to the axle 102 from each of theplurality of resistance mechanisms 106 a, 106 b 106 c and 106 d is equalto a total force applied to the axle 102. The amount of resistanceforces applied to the axle 102 from each of the plurality of resistancemechanisms may be a function of: the surface area of the resistanceelement; the geometry of the resistance element; the diameter of theresistance element; the internal geometry of the housing; the distancebetween the wall of the resistance element and the housing; theresistance element's rotational speed and velocity; the materials of theresistance element, the materials of each the housing; and the materialsof the resistance substance. As described above, embodiments may includeany number of resistance mechanisms. The total resistance force may varydepending on the number of resistance mechanisms used. The embodimentsat FIG. 1 and FIG. 2 include resistance mechanisms 106 a and 106 bhaving different geometries. Other embodiments may, however, includeresistance mechanisms having the same geometries. Embodiments may alsoinclude any number of resistance mechanisms, each having the same ordifferent geometries than other resistance mechanisms. The diameter ofthe resistance element 122 a of resistance mechanism 106 a is alsodifferent from the diameter of the resistance element housing 122 b ofresistance mechanism 106 b. As described above, because of thesedifferent geometries, the amounts of resistance between the respectiveresistance substances 126 a, 126 b and resistance elements 122 a, 122 bmay be different and the forces applied to the axle by resistancemechanisms 106 a and 106 b may be different. FIG. 14 illustratesresistance elements having different surface geometries that may be usedwith the embodiments disclosed herein. For example, resistance elementsmay include double disks, single disks, disks with holes, impellers ineither direction, disks with single or multiple ridges, disks withprotrusions, disks with intrusions, disks with ridges and disks withwaves.

Because the forces applied to the axle 102 from each respectiveresistance mechanism 106 remain substantially constant at a constantvelocity, a force from each respective resistance mechanism 106 may bedetermined by estimating an average velocity of the axle for apredetermined time period or a predetermined stroke length, where astroke length can be determined by observing a number of rotations ofthe axel. Accordingly, respective forces (e.g., 5 pounds) may beattributed to each respective resistance mechanism 106. For example,respective forces of 5 pounds may be attributed to force mechanism 106 band 106 d and respective forces of 10 pounds may be attributed to forcemechanism 106 a and 106 c. The total force applied to the axle 102 maythen be selected in 5 pound and 10 pound increments using thecorresponding resistance engaging device 128 a, 128 b, 128 c and 128 d,as shown at FIG. 1. In other embodiments, force mechanisms capable ofapplying any amounts of resistance forces may also be used. For example,a 5 pound force mechanism, a 10 pound force mechanism, a 20 pound forcemechanism and a 40 pound force mechanism may be used to achieve aresistance force of 75 pounds in 5 pound increments. Force mechanismscapable of applying any amounts of resistance forces less than 5 poundsand greater than 40 pounds may also be used. In some embodiments, forcemechanisms may be used to achieve a resistance force in incrementsdifferent than 5 pound increments.

As shown in the embodiment at FIG. 1, the modular resistance forcesystem 100 may be configured efficiently by arranging the components ofthe modular resistance force system 100 to fit within a spherical outershell 134. For example, as shown at FIG. 1, resistance mechanisms 106 aand 106 b may be arranged on one side of the spool mechanism 104 andresistance mechanisms 106 c and 106 d may be arranged on the opposingside of the spool mechanism 104. Further, the resistance mechanisms 106a, 106 b, 106 c and 106 d may decrease in diameter as they extendfarther from each of the opposing sides of the spool mechanism 104. Thelocations and geometries of the resistance mechanisms 106 a, 106 b, 106c and 106 d shown at FIG. 1 are, however, merely exemplary. Any numberof resistance mechanisms having different locations and geometries thanthose shown at FIG. 1, but which share the same axis of rotation orparallel axis of rotation may be used to apply resistant forces toaxles.

In some embodiments, modular resistance force systems may be used tosimulate forces provided by other exercise devices of any geometry suchas a dumbbell and a kettleball. For example, as shown at FIG. 5A throughFIG. 5C, the modular resistance force system 500 may simulate forcesprovided by a dumbbell by including a handle 502 to join resistancemechanisms 106 housed in outer casings 107 a and 107 b at opposite endsof handle 502. The modular resistance force system 500 may also includea first spool mechanism 504 adjacent resistance mechanisms 106 a and 106b in casing 107 a and a second spool mechanism 506 adjacent resistancemechanisms 106 c and 106 d in casing 107 b. Modular resistance forcesystem 500 may also include individual switches 128 as the resistanceengaging devices and combination resistance engaging devices 508 eachcoupled to the resistance mechanisms 106. In this system, the resistanceassembly works very similar to a barbell with iron plates on eitherside, commonly referred to as “free weights.” Any number of resistancemechanisms having different locations and geometries than those shown atFIGS. 5A and 5B may be used to apply resistant forces. In someembodiments, such as shown in FIG. 5B, additional external elements canalso be added. For example, using joiners 508, a straight barbell 513can be coupled to resistance mechanism 500, allowing free weights toalso be added to the resistance to enhance the experience.

As shown in the embodiment at FIG. 6, the coilable-uncoilable element110 (e.g. spool mechanism 104, which wraps around spool 116, as shown inFIG. 1) may include a holding element 602 having a handle 604 configuredto be held by a user to aid in one or more exercises. Other holdingelements, such as barbells, footstraps, and ropes may also be included.In some embodiments, as shown at FIG. 7, a bar attachment 702 may beconfigured to hold external objects, such as bar 704, that may be heldby a user 706. Referring to FIG. 6, the modular resistance force system100 may also include a foot element 606 removably attached to anopposite side of the modular resistance force system 100. Accordingly,the foot element 606 may be used to prevent the modular resistance forcesystem 100 from moving in the direction 114 while the coilable device110 is pulled in the direction 114. For example, the securing mechanism606 may include an anchoring element 608. In one aspect, a user 706 mayplace a foot on anchoring element 608 to secure the foot while pullingon the handle 604. In other aspects, the foot element 606 may beattached to other external objects, such as for example, a tree, treebranches, doors, cross beams in houses, etc. so that the user 706 maypull the coilable-uncoilable element 110 while the modular resistanceforce system 100 remains attached to the external object.

FIG. 8 illustrates a list of different uses and embodiments of themodular resistance force system 100. The external fitness product mayinclude, but is not limited to a climbing product, a bicycle product, arowing machine product, and a climbing product, such as a stair climbingproduct and a rock climbing product. The external fitness product mayinclude any product that applies a resistance force. The modularresistance force system 100 may be coupled to an external product usingvarious coupling elements, such as belts that may be used to transferthe resistance force to other elements, such as wheels and pedals. Theexternal fitness product may include any product, sport or otherwise,that could use an electro-magnetic brake or other mechanism to apply aresistance force. The external fitness product may also include aproduct that typically lifts iron plates or another pulley mechanism toapply a resistance force. The external fitness product may include agear or pulley that transfers resistance from another element thatincludes at least one of another axle, cord, strap, gear, or pulley.Another external fitness product may be a sport ball or boxing bag.Other examples of external fitness products are shown at FIG. 13Athrough FIG. 13C and FIGS. 15 and 16. In some embodiments, one or moremodular resistance force systems 100 may be used as sport specifictraining products, such as those shown in FIG. 13A through FIG. 13C andFIG. 15. For example, as shown at FIG. 15, a modular resistance forcesystem 100 may be used with jump training for basketball, volleyball,etc.

As shown in FIG. 15, athletes may train to improve a vertical leap withweighted resistance. Unlike traditional weights, the exemplaryembodiment shown in FIG. 15 may allow athletes to land with noadditional weight, preventing jarring to the muscular-skeletal system.Like jumping or hitting a baseball, most movements in sports use anexplosive contraction of muscles followed by a controlled transition tothe next movement. Systems that store energy and try to pull the athleteback to an initial position will hinder the natural flow of themovement.

As shown in the embodiment at FIG. 9, a fitness system 900 may includemultiple modular resistance force systems 100 that may be coupledtogether to produce a combined force. For example, as shown at FIG. 9,the respective coilable devices 110 for each of the modular resistanceforce systems 100 may be combined into a single resistance force thatresists movement in the direction opposite of arrow 902. The respectivecoilable-uncoilable elements 110 may be coupled to an external objectvia extension 904. In other embodiments, any number of the modularresistance force systems 100 may be combined to produce a totalresistance force that resists movement in a direction. Although theexemplary modular resistance force systems 100 shown at FIG. 9 arecoupled via coupling ring 906, modular resistance force systems 100 maybe coupled with other devices, and may be removable from each other orfixedly attached to each other.

FIG. 17A through FIG. 17D are drawings illustrating modular resistanceforce systems that may be used for physical rehabilitation. As shown inFIG. 17A, embodiments may be used to allow braces to assist recoveringmuscles. As shown in FIG. 17B, embodiments may provide workoutopportunities for the physically challenged and cognitively impaired. Asshown in FIG. 17C, embodiments may replace stacks of iron plates, allowhome gym and PT systems to be lighter weight and less expensive. Becausebuilding muscles on one side of the body will build recovering muscleson the other side of the body, embodiments, such as shown in FIG. 17Dmay be used to allow patients to develop strength while they are stillin bed to prepare for the day they will walk again. Embodiments includemodular resistance force systems which do not develop any contractingforce, thereby providing for safer workouts. When the patient gets tootired or too weak to continue, they can simply release the hand grip andnothing will accelerate dangerously toward others.

FIG. 18A through FIG. 18C are axonometric drawings of an exemplarymodular resistance force system having a plurality of resistanceelements and a single stationary outer housing that can be used with theembodiments disclosed herein. As shown in FIG. 18A, the inner axle mayinclude multiple segments. The two outermost resistance disks may beselected to add resistance or not add resistance when the sleeve is slidinto the locked or unlocked positions. As shown in FIG. 18B when theaxles are unlocked, the sleeve does not connect the two axle segments sothe outermost resistance disk does not turn. As shown in FIG. 18C, whenthe axles are locked together, all of the disks may turn relative to theouter casing creating resistance.

FIG. 10 is a block diagram of an exemplary fitness system 1000illustrating a modular resistance force system 100 in communication withan external device 1006. As shown, the modular resistance force system100 may include one or more sensors 1002. The one or more sensors 1002may be coupled to the axle 102, the one or more spool mechanisms 104 andthe one or more resistance mechanisms 106. The one or more sensors 1002may be configured to sense information associated with at least one ofthe axle 102, the one or more spool mechanisms 104 and the one or moreresistance mechanisms 106. In some embodiments, one or more sensors 1002may include individual sensors coupled to the axle 102, the one or morespool mechanisms 104 and the one or more resistance mechanisms 106,respectively.

It is contemplated that forces (e.g., torque, pressure) applied byresistance mechanisms to axles may be sensed by sensors in the vicinityof, embedded in, integral with, adjacent to, locally directed at, orotherwise associated with and in proximity to axles and by the one ormore resistance mechanisms. Sensors may include one or more opticalsensors, such as an optical sensor pointed at a reflecting element orportion of the spindle. User interface elements may include buttonscoupled to electrical switches to select the resistance levels.

The information sensed by the one or more sensors 1012 may includeinformation indicating at least one of: a number of rotations of axle102; a rate of rotations of the axle 102 over a period of time; a strokelength; and an amount of resistance applied to the axle 102. In someembodiments, the one or more sensors 1012 may include a heart ratesensor configured to sense the heart rate of a user.

Modular resistance force system 100 may also include a communicationssystem 1004. Communications system 1004 may be configured to at leastone of: (i) transmit the sensed information received from the sensor1002 to the external devices 1006 and (ii) receive external informationfrom external device 1006. Embodiments may include more than oneexternal device 1006, which may include any device having a processorcapable of processing the information described herein, such as personalcomputers such as desktops, portable devices such as laptops, tabletsand cell phones. Communications system 1004 may include a modularresistance force system input/output interface 1008 and/or modularresistance force system network interface 1010. In some embodiments, thefitness system 1000 may include processor 1012. Other embodiments mayinclude more than one processor 1012. As shown at FIG. 10, processor1012 may be configured to allow the communications system 1004 totransmit the sensed information received from sensor 1002 to externaldevice 1006.

Modular resistance force system 100 may also include a display 1014. Insome embodiments, the display 1014 may also serve as the user interface.For example, the display 1014 may include a touch screen (not shown) toserve as the user interface. In other embodiments, system 100 may alsoinclude a separate user interface 1020 that may include components, suchas buttons and switches.

In the embodiment shown at FIG. 11, exemplary fitness system 1100 mayinclude a computer 1102 electronically coupled to the modular resistanceforce system 100 via a modular resistance force system input/outputinterface 1008 and wire 1104. FIG. 11A is a close-up view of theexemplary modular resistance force system shown at FIG. 11. Modularresistance force system 100 may send the sensed information to computer1102 via modular resistance force system input/output interface 1008 andwire 1104. In some embodiments, modular resistance force system 100 maywirelessly send the sensed information to external device 1006 via amodular resistance force system network interface 1010. In otherembodiments, external devices may include portable electronic devices(e.g., smart phones), servers, workstations, information technologysystems (e.g., Electronic Health Record (EHR) and ComputerizedPrescriber Order Entry (CPOE)), medical systems, network processors,networks, interactive video games, sports science systems, programs totrack progress, or other external devices capable of receiving, storing,manipulating, summarizing, organizing, displaying, processing and/ortransmitting information.

FIG. 11B and FIG. 11C are axonometric drawings that illustrate differentphysical states of the exemplary modular resistance force system shownat FIG. 11. As shown at FIG. 11 B, foot plates 1112 a and 1112 b mayfold up for easy storage and portability. When in the down position,foot plates 112 a and 112 b allow the handle 1110 to be pulled upward.As shown at FIG. 11C, handle 1110 coupled to the coilable-uncoilableelement 110 may pivot using spindle 1114.

In some embodiments, the processor 1012, display 1014 and user interface1020 of the resistance force system 100 itself may be used to receive,transmit, display and process all information. In other embodiments, theresistance force system 100 may not include a processor, display or userinterface and components (shown at FIG. 12) of an external electronicdevice 1106, such as computer 1102 may be used to receive, transmitdisplay and process all information. In other embodiments, components ofthe system 100 and the external device, such as computer 1102 may beused to receive, transmit display and process information.

FIG. 12 is a block diagram of a processing system 1200 of an externaldevice 1006, such as a personal computer 1102. Computer 1102 may includeone or more of the components shown at FIG. 12. For example, theprocessing system 1200 may include a processor 1202, one or moreinternal storage devices 106, 108 (e.g. a non-volatile storage device, arandom access memory (RAM)), a processing system input/output (I/O)interface 1210, a processing system network interface 1212, an externalstorage device 1214, a user interface 1216 and a display 1218. Theprocessor 1202 may be operatively coupled to other components via bus1204.

In some embodiments, display 1218 of processing system 1200 may be usedto display information, such as the sensed information from sensor 1002,to a user 706 for monitoring different parameters of an exerciseroutine. In some embodiments, processing system 1200 may be a linked toa network 1106 via the network interface 1212 for transmitting thesensed information to one or more other external devices 1006. Thenetwork interface 1212 of processing system 1200 may be a wireless orhard-wired interface. In some embodiments, the network interface 1212may include any device suitable to transmit information to and fromanother device, such as a universal asynchronous receiver/transmitter(UART), a parallel digital interface, a software interface or anycombination of known or later developed software and hardware. Thenetwork interface 1212 may be linked to various types of networks,including a local area network (LAN), a wide area network (WAN), anintranet, a virtual private network (VPN) and the internet.

Processing system 100 may send the sensed information and/or processedinformation to other external devices via one or more networks or backto system 100 to modify the settings. For example, the sensedinformation and/or processed information may be transmitted via anetwork 1106, such as the internet to another external device (notshown), such as a medical office computer or a portable electronicdevice where the information may be monitored by a doctor or physicaltherapist. In some embodiments, external information may be received bythe communications system 1004 via the network interface 1212. Theexternal information may include the exercise prescriptions that includeinstructions sent from a doctor or physical therapist via the network tobe completed by a user of the modular resistance force system. Theinformation sensed by sensors 1002 and the external information receivedthrough network 1106 may be displayed on display 1102. The user 706 maythen compare the sensed information to the prescribed externalinformation to monitor the status of the prescription.

In some embodiments, the modular resistance force system 100 may alsoinclude a display 1014. Display 1014 may be disposed on any surface ofthe modular resistance force system 100, such as on a surface of housing1108, from which the display 1014 may be viewed by the user 706. Themodular resistance force system 100 may also include one or moreprocessors 1012 to process the sensed information and/or externalinformation (e.g. prescription information) received from an externaldevice 1006, display the sensed information and the external informationon the display 1014 of the modular resistance force system 100 and/orcontrol components of the modular resistance force system 100.

In some embodiments, the modular resistance force system 100 may alsoinclude one or more storage devices 1018 which may include instructionsfor causing the one or more processors 1012 to transmit the sensedinformation received from the one or more sensors 1002 to one or moreexternal devices 1006 and receive the external information from the oneor more external devices 1006. Storage device 1018 may store the sensedinformation which may be later transmitted to an external device 1006,such as laptop computer 1102 shown in FIG. 11. Storage device 1018 mayalso store external information, such as exercise prescriptions,received from a doctor through a network 1106.

In some embodiments, the modular resistance force system 100 may alsoinclude a user interface 1020 configured to receive instructions from auser instructing the one or more processors 1012 to transmit the sensedinformation received from the one or more sensors 1002 to one or moreexternal devices 1006 and display the external information from the oneor more external devices 1106 on display 1014. The user interface 1020may also indicate the selectable states of the resistance engagingdevices 128 and spool mechanism locking device 136 and may be configuredto cause the resistance engaging devices 128 and spool mechanism lockingdevice 136 to enter different states.

Although the invention has been described with reference to exemplaryembodiments, it is not limited thereto. Those skilled in the art willappreciate that numerous changes and modifications may be made to thepreferred embodiments of the invention and that such changes andmodifications may be made without departing from the true spirit of theinvention. It is therefore intended that the appended claims beconstrued to cover all such equivalent variations as fall within thetrue spirit and scope of the invention.

What is claimed is:
 1. A modular resistance force system comprising: anaxle configured to be rotatable around a rotational axis; and one ormore resistance mechanisms, each of the one or more resistancemechanisms comprising: a resistance element disposed about a portion ofthe axle; a resistance element housing configured to house theresistance element; and a resistance substance disposed between theresistance element and the resistance element housing, wherein eitherthe resistance element or the resistance element housing is selectivelyengaged to rotate with the axle, and a resistance between the resistanceelement and the resistance substance causes a force to be applied to theaxle when the resistance element and the resistance element housing moverelative to each other.
 2. The modular resistance force system of claim1, wherein the resistance between the resistance element and theresistance substance causes a force to be applied to the axle in a firstrotational direction.
 3. The modular resistance force system of claim 1,wherein the force is applied to the axle when the resistance element isselectively engaged to rotate and the resistance element housing isstationary.
 4. The modular resistance force system of claim 1, whereinthe force is applied to the axle when the resistance element housing isselectively engaged to rotate and the resistance element is stationary.5. The modular resistance force system of claim 1, wherein theresistance element is a disc or a cylinder.
 6. The modular resistanceforce system of claim 1, wherein the resistance element is an impeller.7. The modular resistance force system of claim 1, wherein theresistance substance is a fluid comprising at least one of silicone,grease, rubber, an adhesive, or a high tensible material.
 8. The modularresistance force system of claim 1, further comprising one or moreresistance engaging devices each configured to have selectable statesthat comprise: (i) an engaging state which causes the resistance elementand the resistance element housing to move relative to each other andcauses the force to be applied to the axle; and (ii) a disengaging statewhich allows the corresponding resistance element housing and thecorresponding resistance element to move together.
 9. The modularresistance force system of claim 1, wherein the corresponding resistanceelement housing comprises protrusions, and the one or more resistanceengaging devices prevents the corresponding resistance element housingfrom rotating by engaging the protrusions.
 10. The modular resistanceforce system of claim 1, wherein the one or more resistance mechanismscomprise a plurality of resistance mechanisms sharing the rotationalaxis and the product of the resistant forces of each of the plurality ofresistance mechanisms is equal in magnitude to a total force applied tothe axle in the first rotational direction.
 11. The modular resistanceforce system of claim 10, wherein the plurality of resistance mechanismscomprise: a first resistance mechanism configured to apply a first forceto the axle when a first resistance element and a first resistanceelement housing of the first resistance mechanism move relative to eachother; and a second resistance mechanism configured to apply a secondforce to the axle when a second resistance element and a secondresistance mechanism housing of the second resistance mechanism moverelative to each other, and the first force and the second force aredifferent.
 12. The modular resistance force system of claim 1, whereinthe plurality of resistance mechanisms comprise a first resistancemechanism and a second resistance mechanism, and the first resistancemechanism is coupled to the second resistance mechanism via a joiningelement.
 13. The modular resistance force system of claim 1, furthercomprising a spool mechanism having: a coilable-uncoilable elementconfigured to cause the axle to rotate in a second rotational directionopposite the first around the rotational axis when thecoilable-uncoilable element uncoils around the rotational axis; and atleast one spring-force mechanism coupled to the coilable-uncoilableelement and configured to apply a spring force to cause thecoilable-uncoilable element to coil around the rotational axis.
 14. Themodular resistance force system of claim 13, further comprising a spoolmechanism locking device configured to prevent the coilable-uncoilableelement from uncoiling and coiling around the rotational axis.
 15. Amodular resistance force system comprising: an axle configured to berotatable around a rotational axis; a plurality of resistance elementsdisposed about portions of the axle; a housing configured to house theplurality of resistance elements; and a resistance substance disposedbetween the plurality of resistance elements and the resistance elementhousing, wherein either the resistance element or the resistance elementhousing is selectively engaged to rotate with the axle and cause a forceto be applied to the axle.
 16. The modular resistance force system ofclaim 15, wherein the one or more resistance elements are selectivelycaused to move relative to the housing.
 17. A modular resistance forcesystem comprising: an axle configured to be rotatable around arotational axis; and one or more resistance mechanisms, each of the oneor more resistance mechanisms comprising: a resistance element disposedabout a portion of the axle; a resistance element housing configured tohouse the resistance element; and a resistance substance disposedbetween the resistance element and the resistance element housing,wherein either the resistance element or the resistance element housingis selectively engaged to rotate with the axle and cause a force to beapplied to the axle; one or more sensors configured to sense informationassociated with at least one of: (i) the axle; and (ii) the one or moreresistance mechanisms; and a communications system configured to atleast one of: (i) transmit the sensed information received from the oneor more sensors to one or more external devices; and/or (ii) receiveexternal information from the one or more external devices.
 18. Themodular resistance force system of claim 17, further comprising a switchthat causes the resistance element and the resistance element housing tomove relative to each other, wherein the one or more sensors are furtherconfigured to sense information associated with the switch.
 19. Themodular resistance force system of claim 17, further comprising: acoilable-uncoilable element configured to cause the axle to rotate in asecond rotational direction opposite the first around the rotationalaxis when the coilable-uncoilable element uncoils around the rotationalaxis; and a spindle configure to rotate with the coilable-uncoilableelement, wherein the one or more sensors are further configured to senseinformation associated with the spindle.
 20. The modular resistanceforce system of claim 17, wherein the one or more sensors are opticalsensors.
 21. The modular resistance force system of claim 17, whereinthe communications system includes a network interface configured to atleast one of: (i) transmit the sensed information to the one or moreexternal devices via one or more networks wired or wirelessly and/or(ii) receive the external information from the one or more externaldevices via the one or more networks wired or wirelessly.
 22. Themodular resistance force system of claim 17, wherein the sensedinformation is information indicating at least one of: a number ofrotations of the axle; a rate of rotations of the axle over a period oftime; a stroke length; and an amount of resistance applied to the axle.23. The modular resistance force system of claim 17, wherein the one ormore sensors include a heart rate sensor configured to sense the heartrate of a user.
 24. The modular resistance force system of claim 17,further comprising a processor configured to cause: the communicationssystem to transmit the sensed information received from the one or moresensors to the one or more external devices; and the communicationssystem to receive the external information from the one or more externaldevices.
 25. The modular resistance force system of claim 17, furthercomprising a memory having instructions for causing the processor toinstruct the communications system to at least one of: (i) transmit thesensed information received from the one or more sensors to the one ormore external devices; and (ii) receive the external information fromthe one or more external devices.
 26. The modular resistance forcesystem of claim 17, further comprising an electronic switch configuredto cause the resistance element and the resistance element housing tomove relative to each other.
 27. A fitness system comprising: (I) one ormore modular resistance force systems each having: an axle configured tobe rotatable around a rotational axis; and one or more resistancemechanisms, each of the one or more resistance mechanisms comprising: aresistance element disposed about a portion of the axle; a resistanceelement housing configured to house the resistance element; and aresistance substance disposed between the resistance element and theresistance element housing, wherein either the resistance element or theresistance element housing is selectively engaged to rotate with theaxle and cause a force to be applied to the axle; and (II) an externalmechanism having one or more components configured to interact with auser, wherein the one or more modular resistance force systems iscoupled to the external mechanism.
 28. The fitness system of claim 27,wherein the external mechanism is a home fitness product from a group ofhome fitness products that comprises a stationary bicycle, a climbingproduct and a rowing product.
 29. The fitness system of claim 27,wherein the external mechanism is a product that applies a rotationalresistance force.
 30. The fitness system of claim 27, wherein theexternal fitness mechanism is a product applies a linear resistanceforce.
 31. The fitness system of claim 27, wherein the external fitnessmechanism is a product that uses gravity to apply a resistance force.32. The fitness system of claim 27, wherein the external fitnessmechanism comprises a gear or a pulley that transfers resistance fromanother element that includes at least one of another axle, cord, strap,gear, or pulley.